Dan Simmon's "The Terror" is to the Franklin Expedition what "Pan's Labyrinth" is to Franco's Spain. That is to say, the book is as much a mix of history, horror and fantasy as Del Toro's film is, and achieves this pastiche with an equal level of success. The premise is simple; Simmons imagines the doomed expedition, trapped not only by the elements of the Arctic, but by something more elemental, a physical monstrosity which is killing the men off. I have likened it to John Carpenter's The Thing, but with Kurt Russell in the role of Captain Francis Crozier of the H.M.S. Terror, a role Russell would be sufficiently aged enough to play at present. I'm not implying the "thing on the ice" is an alien. I'm not going to say anymore about the nature of the beast, and have betrayed no spoilers in revealing its presence in the book. The book's jacket liner will tell you as much, and the first chapter makes several references to its presence and malevolent nature. I will warn you that you'll need to read the whole book to find out exactly what "it" is, and that many might find the journey too long and arduous, although I'm of the opinion that this was Dan Simmon's intention.
In truth, the monster is an interesting sideline to the story, but Simmons is thoroughly concerned with his cast of historical characters, especially Crozier, and the reason for turning the pages is the growth and development of the men of the Expedition, not the unraveling of the mystery surrounding the monster's identity, though that certainly makes for an enticing motivator. As with "Pan's Labyrinth," the most monstrous actions are done on the part of the humans, and the historical facts of cannibalism on the expedition, when they finally rear their ugly head, outstrip the fantastical "terror" by far.
Simmons has a deft hand when it comes to explicating historical information within the action of a page-turning scene. He is far more fond of showing us than telling us, and passages that would have been dry exposition in the hands of a lesser word-smith are rendered page-turners, as is especially the case with a surgery late in the book. Ultimately though, Simmons is about the men within this historical setting. The book is historical insofar as it appears thoroughly researched and meticulously crafted to produce verisimilitude. It is horror insofar as it produces fear, employing all the means Stephen King laid out in "Danse Macabre" for evoking horror, even the last resort, the "gross-out." It is fantasy insofar as it deals with the supernatural, or at the very least the possibility thereof. And additionally, it is philosophical, pondering the question of whether or not Hobbes was right in his "Leviathan" when he claimed that life is poor, nasty, brutish, and short. The interplay between the historical and the fantastic hold that question in tension until the very last page of the book, and possibly beyond, leaving the reader to ponder how they themselves are stuck in the ice, trapped in a cold, violent world which seeks to devour them.